A comparative on the thermal decomposition and fire‐extinguishing performance of C5F8 and C5F7Cl

• Published in: International journal of quantum chemistry Vol. 123; no. 20
• Main Authors: Chang, Zhenxiang, Yu, Rourou, Li, Shukai, Guo, Yueying, Tan, Zhaoyang, Zhang, Xiao, Liu, Jiexiang
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 15.10.2023; Wiley Subscription Services, Inc
• Subjects: Alkenes; Chemistry; Chlorine; Cycloalkanes; density functional theory; Extinguishing; fire suppression; Fluorination; Halon substitute; Physical chemistry; Pyrolysis; pyrolysis mechanism; Quantum physics; theoretical and experimental insights; Thermal decomposition
• ISSN: 0020-7608; 1097-461X
• DOI: 10.1002/qua.27198

Compared with fluorinated cycloalkanes and liner olefins, the degradation of chlorofluorocycloolefins is much easier with good environmental friendliness. However, the fire‐extinguishing performance of chlorofluorocycloolefins has been rarely explored. In this study, the fire‐extinguishing performance and working mechanism of octafluorocyclopentene (C5F8) and 1‐chloro‐2,3,3,4,4,5,5‐heptafluorocyclopentene (C5F7Cl) were studied by combined experimental and theoretical approach. It was found that, compared to C5F8, the asymmetry of C5F7Cl agent with the chlorine atom possesses a reduced energy barrier in pyrolysis process and its reaction with OH· radicals. Moreover, chlorine‐containing unsaturated active groups and CF2· radicals generated in C5F7Cl pyrolysis can effectively capture flame radicals. As a result, a relatively low minimum extinguishing concentrations (MECs) for suppressing methane‐air (5.37 vol%) and propane‐air flame (5.93 vol%) is achieved outperforms that of C5F8 (6.73 and 7.74 vol%), even better than reported fluorinated cycloalkanes and chlorofluoroolefins agents. This study shows that chlorofluorocycloolefins are promising Halon substitutes over perfluorocyclic olefins in fire‐extinguishing performance. Recently, due to the urgency and necessity of Halon replacement, the search and development of more environmentally safe fire‐extinguishing agents has attracted extensive research efforts. In this paper, the thermal decomposition mechanism, as well as fire‐extinguishing mechanism and performance of C5F8 and C5F7Cl were studied by DFT calculation and experimental measurements, to analyze the practicability of this proposed Halon substitution product.